1. Black men are more likely than White men to have emphysema with normal spirometry findings.
2. Black women had a slightly higher prevalence of emphysema than White women.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Chronic obstructive pulmonary disease (COPD) is defined as airflow limitation on spirometry with an FEV1/FVC ratio less than 0.7 or less than the lower limit of normal. However, patients with preserved lung function can still have respiratory symptoms, exacerbations, and accelerated lung decline similar to that observed in COPD. It is also understood that racial disparities exist in COPD outcomes and rates of COPD underdiagnosis. Therefore, there is a gap in knowledge as to understanding the prevalence of emphysema on CT among those with normal spirometry findings, and whether differences exist in the prevalence of emphysema among Black and White adults. Overall, this study found that emphysema is commonly present before spirometry findings become abnormal. Further, the prevalence of emphysema is higher among Black men than White men. This study was limited by the inability to examine CT imaging and spirometry at the same time. Imaging was obtained five years before spirometry, and emphysema is a progressive and irreversible disease, so this may have led to an overall underestimation of the prevalence of emphysema. Nevertheless, these study’s findings are significant, as they demonstrate that emphysema can present before finding abnormal spirometry results and that these rates of emphysema may be impacted by race.
In-Depth [observational study]: The CARDIA (Coronary Artery Risk Development in Young Adults) study is a multicenter, population-based, longitudinal cohort study that enrolled 5,115 Black and White participants aged 18 to 30 years. Spirometry and clinical data were taken from 2015 to 2016 and CT scans were obtained from 2010 to 2011. The primary outcome measure was the prevalence of emphysema among participants with various measures of normal spirometry results, including an FEV1/FVC ratio greater than or equal to 0.7 or greater than or equal to the lower limit of normal, stratified by sex and self-reported race. Outcomes in the primary analysis were assessed via sex-specific multivariate logistic regression to calculate the adjusted prevalence of emphysema as well as age, smoking status, and pack-years of smoking. Based on the primary analysis, among patients who had emphysema despite normal spirometry results with a race-specific FEV1 between 80 and 99% predicted. Emphysema prevalence was 3.9 fold (95% Confidence Interval [CI], 2.1 to 7.1 fold) higher among Black men than White men and 1.9 fold higher (95% CI, 1.0 to 3.8 told) higher among Black women than White women. In patients with FEV1 between 100% and 120% of predicted, Black men had a 6.4 fold (95% CI, 2.2 to 18.7 fold) higher prevalence of prevalence than White men. Black and White women had a similar prevalence of emphysema (2.6% and 2.0%). Overall, this study demonstrates that emphysema is present even when there are normal spirometry findings and that the prevalence of emphysema is higher among Black men than White men.
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